/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.classfile.instruction;

import proguard.classfile.*;
import proguard.classfile.attribute.CodeAttribute;
import proguard.classfile.instruction.visitor.InstructionVisitor;

/**
 * This Instruction represents a simple instruction without variable arguments or constant pool references.
 *
 * @author Eric Lafortune
 */
public class TableSwitchInstruction extends SwitchInstruction {
    public int lowCase;
    public int highCase;

    /**
     * Creates an uninitialized TableSwitchInstruction.
     */
    public TableSwitchInstruction() {}

    /**
     * Creates a new TableSwitchInstruction with the given arguments.
     */
    public TableSwitchInstruction(byte opcode, int defaultOffset, int lowCase, int highCase, int[] jumpOffsets) {
        this.opcode = opcode;
        this.defaultOffset = defaultOffset;
        this.lowCase = lowCase;
        this.highCase = highCase;
        this.jumpOffsets = jumpOffsets;
    }

    /**
     * Copies the given instruction into this instruction.
     * 
     * @param tableSwitchInstruction the instruction to be copied.
     * @return this instruction.
     */
    public TableSwitchInstruction copy(TableSwitchInstruction tableSwitchInstruction) {
        this.opcode = tableSwitchInstruction.opcode;
        this.defaultOffset = tableSwitchInstruction.defaultOffset;
        this.lowCase = tableSwitchInstruction.lowCase;
        this.highCase = tableSwitchInstruction.highCase;
        this.jumpOffsets = tableSwitchInstruction.jumpOffsets;

        return this;
    }

    // Implementations for Instruction.

    public Instruction shrink() {
        // There aren't any ways to shrink this instruction.
        return this;
    }

    protected void readInfo(byte[] code, int offset) {
        // Skip up to three padding bytes.
        offset += -offset & 3;

        // Read the three 32-bit arguments.
        defaultOffset = readInt(code, offset);
        offset += 4;
        lowCase = readInt(code, offset);
        offset += 4;
        highCase = readInt(code, offset);
        offset += 4;

        // Read the jump offsets.
        jumpOffsets = new int[highCase - lowCase + 1];

        for (int index = 0; index < jumpOffsets.length; index++) {
            jumpOffsets[index] = readInt(code, offset);
            offset += 4;
        }
    }

    protected void writeInfo(byte[] code, int offset) {
        // Write up to three padding bytes.
        while ((offset & 3) != 0) {
            writeByte(code, offset++, 0);
        }

        // Write the three 32-bit arguments.
        writeInt(code, offset, defaultOffset);
        offset += 4;
        writeInt(code, offset, lowCase);
        offset += 4;
        writeInt(code, offset, highCase);
        offset += 4;

        // Write the jump offsets.
        int length = highCase - lowCase + 1;
        for (int index = 0; index < length; index++) {
            writeInt(code, offset, jumpOffsets[index]);
            offset += 4;
        }
    }

    public int length(int offset) {
        return 1 + (-(offset + 1) & 3) + 12 + (highCase - lowCase + 1) * 4;
    }

    public void accept(Clazz clazz, Method method, CodeAttribute codeAttribute, int offset,
        InstructionVisitor instructionVisitor) {
        instructionVisitor.visitTableSwitchInstruction(clazz, method, codeAttribute, offset, this);
    }
}
